The invention relates to a clutch for the shiftable connection of a primary part to a secondary part, said clutch comprising a dog clutch consisting of a first and of a second clutch half.
Positive clutches of this type are used in the drive train of motor vehicles for the cutting in of drive axles or for the blocking of differential gears. Engagement and disengagement take place by means of the axial displacement of one of the clutch parts, the dogs or teeth provided on their end faces being brought into engagement or out of engagement. Thus, with a minimal installation space, a very high torque can be transmitted positively. The displacement of one clutch part may take place by means of an actuator acting in both directions or, as described in DE-C-4113 128, by means of an actuator acting in only one direction. This requires teeth or dogs with undercut flanks and with a spring acting in the opening direction between the two clutch halves, so that the clutch opens automatically when the torque lapses.
The term “undercut flanks” is to be understood to mean that the dogs of the clutch have, in circumferential section, essentially the form of a trapezium, of which the shorter of the two parallel sides faces away from the counterdogs.
During disengagement and engagement, frictional forces act between the flanks of the clutch dogs, and these frictional forces delay disengagement and have to be overcome by the actuator. If the clutch is designed in such a way that it is disengaged automatically when the torque lapses, this then also means that it cannot be disengaged under load. Both must be avoided when a rapid opening of the clutch in the drive train of a motor vehicle is required, for example for cooperation with electronic action on the brake system (for example, ABS).
The object of the invention is to ensure a rapid opening of a generic clutch even under load.